Manufacture of wrought iron



Oct-19, 1937. J. ASTON ET AL.

MANUFACTURE OF WROUGHT IRON Filed July 30, 1952 INVENTORS m. N f

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Patented oct. 19, 1937 iJNlTED STATES PATENT OFFICE MANUFACTURE OF WROUGHT IRON Sylvania Application July 30, 1932, Serial N0. 626,986

3 Claims.

This invention relates broadly to the manufacture of wrought iron, and more particularly to the manufacture of Wrought iron in accordance with the now well known Aston process. The invention further relates to certain improvements in the manufacture of Wrought iron and which are particularly adaptable to the Aston process.

The invention still further relates to certain improved methods for the manufacture of wrought iron, which methods result in numerous advantages over the manufacture of wrought iron by the Aston process as heretofore known. f

The Aston process for the manufacture of wrought iron is now Well known and, in a preferred manner of procedure, comprises pouring molten ferrous material into a slag bath so that the solidified or partly solidified granules of ferrous material formed during the pouring are individually coated with slag and welded together to form at the bottom of the slag receptacle a compressible mass or ball of wrought iron. rIhe ball thus formed can be compressed to form a bloom which may then be rolled or reduced to a billet or any other desired form.

In order to insure the uniform distribution of the molten ferrous material throughout the slag, and to avoid excessive heating of any one portion of the latter, there have been devised certain methods of and apparatus for automatically pouring molten ferrous material into a slag bath in such a manner that the desired result is obtained. Such methods are specifically described and claimed in Wille Patent No. 1,890,660, granted December 13, 1932, and such apparatus is specifically described and claimed in Wille Patent No. 1,933,577, granted November 7, 1933.

We have devised certain methods of procedure in the manufacture. of wrought iron by the Aston process designed to facilitate the operations, reduce the amount of time required for the completion thereof so that the process may be carried out more efficiently and more expeditiously, and otherwise increase the efficiency of the operation and maintain the high standard of quality of the product. Other methods and apparatus described herein are described and claimed in the copending application of Herman A. Brassert, Serial No. 626,984, filed of even date herewith.

A plant for the manufacture of wrought iron is provided which comprises means for supplying molten ferrous material, means for supplying slag, a press, and one or more shotting machines. Each shotting machine preferably comprises a reciprocable platform carrying a table adapted for rotary movement. A tiltable ladle is preferably supported on the table and means are preferably provided for reciprocating the platform, rotating the, table and tilting the ladle, all of said operations being preferably performed automatically. The reciprocable platform is preferably supported by the beam of a platform scale so that the amount of ferrous material poured from each machine into a receptacle of slag positioned therebeneath may be accurately determined.

In the plant arrangement previously mentioned, a track is preferably provided to connect the slag furnace or furnaces and shotting machine. or machines and to lead to a slag transfer station, preferably adjacent a ball press, whereby cars carrying slag receptacles may be readily shifted from one point in the plant to another. Briefly, the arrangement in a present preferred embodiment is such that empty slag receptacles may be positioned adjacent the slag furnace to receive a charge of slag. The cars are then moved to position the slag receptacles beneath the shotting machines which pour thel required amount of molten ferrous material into the slag and distribute it therethrough. In order to increase the speed of production a plurality of shotting `machinesv are employed whereby several slag receptacles may simultaneously receive a charge of molten ferrous material into their respective slag contents. The cars are shifted from the shotting machines, excess slag is transferred from the'slag receptacles and the balls are removed therefrom adjacent the press for treatment therein. Preferably the excess slag is decanted from each slag receptacle., and it is found highly advantageous to transfer the excess slag, either by decantation or otherwise, into another slag receptacle disposed at the same level, preferably directly, and this may conveniently .be done by lifting and tilting the slag receptacle, and, after the desired quantity of excess slag has been removed, dumping out the ball, preferably directly into the press. This feature is described and claimed in the copending application of James Aston and Herman A. Brassert, Serial No. 626,985, filed of even date herewith. The excess slag is preferably reused for the formation of one. or more additional balls, with or without additions. We prefer to replenish the excess slag with additional molten slag.`

The means for supplying molten ferrous material may be of any suitable or well known type, and in the production of limited quantities of wrought iron it is found that certain advantages are obtained by using one or more cupolas whereille metal is melted and one or more Bessemer converters to which the melted metal is transferred for refining. The converter or converters may be tapped into a transfer receptacle which delivers the refined metal to the shotting machines.

The invention may be fully understood by reference to the accompanying drawing taken in connection with the following description, the drawing illustrating a present preferred embodiment of the invention which is nowise to limit the scope thereof as it is intended merely as an example. Other details, objects and advantages of the invention will become apparent as the description proceeds.

The drawing is a schematic diagram of a plant layout which we have provided for the rapid and efficient production of wrought iron by the Aston process. i Y

Referring more particularly to the drawing, there are provided three cupolas, designated generally by reference numeral 2, erected Within an enclosure 3 and which may be of standard or well knownl construction. There are also provided two Bessemer converters which may be of standard or well known construction, such converters being designated generally by reference numeral 8. The usual converter accessories are provided.

A platform 9 is provided which extends longitudinally from the cupolas past the converters. A track l0 is provided on the platform, such track extending from a point beneath the metal runouts of the cupolas past the converters. A transfer car provided with a tilting ladle operates on the track I0. VThe-molten metal from the cupolas is tapped into thetilting ladle, the slag is raked off and the metal is otherwise treated as may be desired, and the car is then moved to a positionV opposite one or the other of the converters 8 and the molten metal is poured into such converter. The converter is then rotated to blowing position and the metal is Bessemerized or refined.

'I'he cupolas may be tapped alternately, the three cupolas furnishing approximately the right amountof metal to keep the converters in operation. The converters may be operated alternately or their operation may be staggered, one converter blowing while the other is being tapped and charged. If smaller capacity is desired one of the converters may be used alone and one or two of the cupolas shut down. In any event, the mechanism described produces batches of refined ferrous material at spaced intervals. The amount of material in each batch and the intervals between batches will be controlled so as to coordinate with the shotting apparatus presently to be referred to.

There are provided a pair of slag furnaces, designated generally by reference numeral I3, which are preferably of the tilting open hearth type and which are provided with run-outs I4. These furnaces may be of standard or well known construction. The slag furnaces produce an iron oxide silicate slag suitable for the formation of wrought iron in accordance Withthe Aston process. If smaller capacity is desired one of the furnaces may be. used alone. In any event, Whether one or bothof the furnaces are used, quantities of molten slag are available at spaced intervals so as to coordinate with the other units of the plant, as will presently be described.

There are provided a plurality of shotting machines designated generally by reference numeral 2| and a press designated generally by reference numeral 22. The shotting machines 2l are mounted on a Working floor or platform 23 which may conveniently be at the same level as the platform 9 and may form a continuation thereof. Trains of slag receptacle cars 24 are adapted to be moved past the furnaces, the shotting machines and the press on a track 25 by means of any suitable source of motive power. An electric locomotive I5 may conveniently be used for this purpose. The track 25 is preferably disposed at the working level of the plant, taken as a whole, which is a substantial distance below the level of the working floor 23 and may conveniently be at the level of the track 21, presently to be described. The specific construction of the shotting machines forms no part of the present invention and therefore will not be described in detail. Such construction is described and claimed in said ccpending application Serial No. 537,856.

Any number of the shotting machines may be used, depending upon the capacity of operation desired. Previous to the shotting operation of any given shotting machine a slag receptacle carried on one of the slag receptacle cars 24 is placed directly beneath the shotting machine. Prior to being placed beneath the shotting machine, however, such slag receptacle is provided with a quantity of molten slag either from the slag receptacle, or both.

Considering, for example, initiation of operation of the plant, and assuming that only two of the.shotting machines are to be operated, a quantity of suitable molten slag is first prepared in one of the slag furnaces, and such furnace is tapped either into a ladle (not shown) carried and manipulated by an overhead crane i6, which ladle in turn supplies the slag to two slag receptacles mounted on cars positioned on the track adjacent the slag furnaces, or into the two slag receptacles themselves, in which case the slag receptacles are lifted from the cars by the overhead crane and in turn held in position to receive the slag tapped from the furnace. The two slag receptacles are preferably lled approximately half full of slag. The cars carrying such two slag receptacles are then moved along the track 25 in the direction of the arrows until the receptacles lie directly beneath the two shotting machines which are to operate as above stated.

Meanwhile molten ferrous material has been prepared in one of the cupolas and has been transferred as above explained to one of the Bessemer converters where it is refined. After completion of the rening operation the converter discharges its contents into a transfer ladle removably mounted on a car movable longitudinally on a track 21 which extends to a position directly opposite the shotting machines. The car is then moved along the track 2l to a position approximately opposite the two shotting machines which are to operate, at which point the transfer ladle is picked up by an overhead crane 63 and a portion of its contents is poured into the shotting ladle of each of the shotting machines which is to operate.

The amount of ferrous material poured into each shotting machine is determined by the scale upon which the shotting machine is mounted. An operator on the platform Watches the scale dial and signals the crane operator when to stop pouring. If convenient the transfer ladle may be completely emptied into the two shotting machine ladles, although if it should be desired to introduce into the shotting machine ladles less than all of the material in the transfer ladle,

. slag furnaces or from excess slag from another the succeeding shotting operation.

such ladle containing the residue of the molten ferrous material is Withdrawn and the molten ferrous material may be maintained in the trans-1 fer ladle until the succeeding shotting operation, when it may be poured into one or more of the shotting machine ladles. This procedure is of advantage when, for example, it is desired to pour relatively small amounts of molten ferrous material into the shotting machine ladles for the purpose of forming relatively small balls of wrought iron. It would be undesirable to proportionately reduce the amount of material in a converter heat, and one converter heat may thus be used for more than one shotting operation. The molten ferrous material in the transfer ladle remains hot enough so that if there is no undue delaybefore the next shotting operation it may be made use of just as thoughit had originally been poured into the shotting machine ladies.

The pouring of the molten ferrous material from the shotting machine ladles into the slag receptacles is .fully described and illustrated in said Wille patents, and as the specic manner of pouring forms no part of the presentinvention it will not be described here in detail.

After the required amount of ferrous material has been introduced into each slag receptacle the cars 24 are removed from beneath the oor 23 to a convenient position for removal of excess slag. It is preferred to remove excess slag at a position adjacent the press 22, and such position will for convenience be called the slag transfer station. It is found desirable to remove excess slag by decanting and to this end it is convenient to lift the slag receptacle and tilt it. An overhead crane il may conveniently be used for this purpose. Excess slag Will thereby be decanted from the receptacle, the ball remaining therein.

The ball is removed from the slag receptacle to the press, this preferably being doneV by substantially inverting the slag receptacle and dumping out the ball. We prefer to dump the `ball directly into the press and then to compress it to form a bloom of wrought iron which may then be given any desired treatment, such as rolling, to produce wrought iron articles.

As the Wrought iron is adap"ed for fabrication into many different products of different sizes and shapes, and as unfinished shapes such as billets, slabs, etc., of different sizes are desirable for producing the Various finished articles, it is likewise desirable to produce in the blooming mill billets and slabs of various different cross-sections and lengths. However, it is impracticable to attempt to form in a blooming mill widely different sizes and shapes of slabs and billets from blooms of standard size. Therefore, provision is made for supplying blooms of various sizes, and as the size of a bloom depends upon the size of the wrought iron sponge or ball, balls of different sizes are made to conform with the products to be rolled on the blooming mill.

While it is ordinarily desirable to empty a shotting machine ladle at each shotting operation, nevertheless if relatively small balls are to be formed the shotting machine ladle may be only partly emptied during one shutting operation and may be completely emptied upon the succeeding operation, or the residue remaining in it after the first shutting operation may be replenished by additional molten ferrous material and part or all of the aggregate 'thus formed may be poured into the slag bath upon The provision of the scalefmakes possible close control of they size of the ball even though only part of the ferrous material is poured out of the shotting machine ladle into the slag bath at one shotting operation, and even though the ferrous material is replenished before the succeeding shotting operation.

It sometimes hap-pens that a relatively small quantity of slabs or billets of a particular size is desired, such, for example, that one small ball Would provide a bloom suitable for rolling into the desired quantity of slabs or billets of the size in question. Provision is therefore made for dividing a heat of refined metal into unequal portions.. A small ball and a relatively large ball, for example, may be formed at the same time. The small ball produces asmall bloom which, in turn, is suitable for rolling in the blooming mill into the desired number of slabs or billets of the desired size. If the entire heat were utilized for the formation of balls of the same size this desirable result would not be possible. Liliewisethe desirable result would not be possible if all of the balls made at one shotting operation should be of the same size.

The provision of the scale also makes possible regulation and control of the rate of pour. As a shotting machine ladle is progressively emptied during shotting, the operator on the platform by Watching the scale dial can observe the decrease in weightofv the shotting ladle and contents, which is equivalent to the weight of the ferrous material poured into the slag bath. By suitably controlling the tilting of the ladle a desired rate of pour can be obtained.V The rate of pour is preferably maintained uniform, although if for any reason it should be desired to do so the rate could be altered during the pour. Certain methods of and apparatus for controlling the pour are described and claimed in the copending application of Edward B. Story `and William T. Case, Serial No. 623,125, filed August l0, 1932.

We prefer to have a second slag receptacle at the slag transfer station during decanting of each slag receptacle and to decant the excess slag directly into the second receptacle. The second receptacle is preferably at the Working level, that is to say, the same level occupied by the first slag receptacle before it is lifted for decanting. This eliminates the provision of a plurality of working levels at the slag transfer station.

It is convenient to utilize a train comprising at least one more slag receptacle car than there are shotting machines in operation. For example, with two shotting machines in operation it would be preferable to use a three-car train, two of the cars having slag receptacles provided with slag and the third car having an empty slag receptacle. After completion of the shotting operation and removal of the train to the slag transfer station one of the lled receptacles would first decant its excess slag into the empty slag receptacle and then dump out its ball into the press, Then the second filled slag receptacle would decant its excess slag into the slag receptacle just emptied and dump its ball into the press, thelast slag receptacle emptied being used as the empty slag receptacle for the succeeding shotting operation. If desired, the last slag receptacle can be held at the slag transfer station until the return of the` two cars having filled receptacles after kthe succeeding shotting operation, whereupon such emptyreceptacle can be placed on its car and the decanting procedure above de- `is repeated. By the use of the improved processes it is possible to speed up the operation sufficiently that the measures previously taken to conserve the heat of the slag can be eliminated. It has heretofore been proposed to conserve the heat of the slag by using a heat insulated slag Y receptacle, this having been found necessary or desirable when the operation was carried out s0 slowly that there was danger that the slag would be too low in temperature for proper ball forma- Y tion by the time the subsequent shotting operation could be carried out. The provision of insulated slagY receptacles entailed additional expense and was also the cause of operating difliculties, and these disadvantages are eliminated by doing away with the insulation for the slag receptacles and returning the slag receptacle Vwith the excess slag to the pouring station so quickly that the slag remains at proper temperature. Uninsulated slag receptacles may therefore be used. Furthermore, uninsulated receptacles need notbe handled so carefully as insulated receptacles and this aids in speeding up the operation.

By uninsulated slag receptacles we mean slag receptacles which do not have insulating material applied previously to their use and of a different character than material contained within the receptacles during use. The slag receptacles used in our process may acquire a skull or lining of solidified slag which may have insulating properties, but such skull or lining does not make our receptacles insulated receptacles within the meaning intended.

VAdditions may be made to the slag before reuse, and we prefer to replenish the molten slag with additional molten slag from the slag furnaces, and preferably with molten slag having the same characteristics or whose analysis is approximately the same as that of the excess slag. To this end the slag receptacle containing the excess slag is preferably moved along the track in the direction of the arrows to a'position adjacent the slag furnace, which position may be termed a slag supply station, where additional slag from the furnace is introduced into the slag receptacle.

Although slag replenishment is ordinarily effected by making the addition to the excess slag after separation of the ball and excess slag, we somtimes prefer to makethe addition in the slag receptacle containing the ballY and excess slag before separation thereof, either at the slag supply station, as above mentioned, or at the slag transfer station. The feature of replenishing at the slag transfer station is described and claimed in the copending application of Charles E. Gross, Serial No. 626,987, led of even date herewith. It may be preferable to make the addition before separation of the ball and excess slag under certain operating conditions, as, for example, when slag has been tapped from one'of the slag furnaces and for some reason the separation of a` ball and the excess slag therewith is delayed. Under such circumstances we prefer to pour the slag from the slag furnace into a slag receptacle containing the ball and excess slag which have not been separated, in order that the slag from the slag furnace may not become undesirably cool by reason of standing for an extended period.

The slag temperature can be controlled by replenishment with molten slag from the slag furnace. During the shotting operation the ferrous material, being hotter than the slag, gives up heat to the slag and the slag therefore becomes appreciably hotter and may become undesirably hot, that is to say, so hot that the proper temperature differential would not be obtained rif it should be attempted to again pour ferrous material into the excess slag. On account of the rapidity with which the operation may be carried out by using the improved processes the excess slag may not cool down to a temperature equivalent, say, to the temperature of the slag tapped from the slag furnace. Consequently the addition of a proper amount of slag from the slag furnace will bring down the temperature of the slag tosuch a point that the desired differential may be obtained. The temperature may be closely controlled by regulating the amount of slag added from the slag furnace.

Occasionally, due to unforeseen interruptions, a batch of excess slag may have to stand so long as to become undesirably cool. As above mentioned, the temperature of such slag was formerly attempted to be maintained by the use of heat insulating material in connection with the slag receptacle. However, the slag can be brought up to such a temperature that the proper differential may be obtained by adding a proper amount of slag from the slag furnace. When the excess slag has cooled down below the temperature of the slag in the slag furnace the greater the amount of slag added from the slag f furnace the higher will be the temperature of the resultant mixture or aggregate.

It is known to be desirable to form a ball having at least one horizontal dimension greater than its vertical dimension, and such a ball may conveniently be formed by utilizing our improved processes even though excess slag is returned without replenishment to the pouring station. The ferrous material may be distributed over the. surface of the slag so as to produce a ball having at least one horizontal dimension greater than its vertical dimension regardless of the height of the slag in the slag receptacle during pouring. Therefore it is possible to reuse the same slag a number of times without replenishment While still obtaining highly desirable results.

The movement of the shotting machines is, of course, stopped before the slag receptacles are moved from under the machines. The shotting ladles are restored to their respective vertical positions for receiving another charge of ferrous material from the transfer ladle and the entire cycle of operations may then be repeated.

We have thus provided methods and apparatus for rapidly and efficiently carrying out the Aston process for the manufacture of wrought iron. The operations of the shotting machines are largely `automatic and a minimum of manual control is necessary. This makes it possible for a comparatively large installation to be controlled by few men with a resulting lowering in costs of production. The plant layout is such that the operation is of the line variety so that no unnecessary transportation of material in process is necessary.

The movement of the shotting machines is such as to secure a uniform distribution of the metal throughout the slag so that a superior quality of Wrought iron is produced.

Although We have illustrated but a single preferred embodiment of our invention, We do not intend to be limited to the specific details thereof since the invention may be practiced in other forms. Minor changes and alterations will be apparent to those skilled in the art and all such changes may be made without departing from the invention as defined by the appended claims.

We claim:

1. A method of making Wrought iron comprising incorporating ferrous material with molten slag in a slag receptacle to form a ball, then adding additional molten slag, and then separating the ball and the excess slag.

2. A method of making Wrought iron comprising incorporating ferrous material with molten slag in a slag receptacle to form a ball, then adding additional molten slag, then separating the ball and the excess slag, and then incorporating ferrous material with the excess slag to form another ball.

3. A method of making wrought iron comprising using and reusing a batch of molten slag for incorporation of portions thereof with ferrous material to form balls of Wrought iron, replenishing said batch of Slag With additional molten slag after formation of a ball of Wrought iron, and .after such'replenishment separating such ball and the excess slag.

JAMES ASTON. EDWARD B. STORY. 

